This invention relates to a physical random number generator adapted to generate the true random numbers by taking out thermal noises generated from a thermal noise generating element such as a resistor or a diode Men no electric current is supplied to the thermal noise generating element and amplifying it by means of an amplifier. A physical random number generator according to the invention can suitably be used for personal identification, coding and other purposes in computer telecommunications and mail-order business because it can perfectly eliminate frauds. A physical random number generator according to the invention is also suitable for generating the probability in various game machines.
Known physical random number generating methods include those for generating random numbers by detecting a random phenomenon of nuclear decay as disclosed in Japanese Patent Applications Laid-Open Nos. 11-161473 and 11-184676 filed by the inventor of the present invention and those for generating random numbers by detecting the light of a light-emitting diode as disclosed in Japanese Patent Application Laid-Open No. 11-145362 also filed by the inventor of the present invention.
A number of random number generators designed to supply an electric current to a resistor and utilize thermal noises from the resistor have been invented and are described in text books on recording mediums.
While a physical random number generator that utilizes the decay products of a radioactive source provides the advantage that it can easily generate the true random numbers, it is accompanied by a number of disadvantages including that it involves a complex manufacturing process and high manufacturing cost because of the use of a radioactive source and that a device with radioactive source has difficulty to be socially accepted because of the regulation of radioactivity and environmental assessment in the use of radioactive substances.
A physical random number generator adapted to generate random numbers by detecting the light from a light emitting diode (LED) by means of a photodiode is advantageous in tat it can generate the true random numbers at relatively low cost However, such a physical random number generator needs new technological developments for integrally forming a LED and a photodiode as a compact unit.
It is impossible to enclose a known random number generators designed to supply an electric current to a resistor in order to utilize it as thermal noise source in a portable card or an integrated circuit (IC) because it requires the use of specifically designed devices including a piece of hardware for generating random numbers and a processing circuit for removing the 1/f noise that are generated as a result of supplying an electric current to the noise source.
Therefore, it is the object in the present invention to provide a random number generator that has a simple configuration with known inexpensive electronic parts and can generate the true physical random numbers at a required generation speed. Such a random number generator can provide the true physical random numbers to any industrial fields at dramatically low cost
The present invention is based on the fact that noises generated from a generating thermal noise element such as a resistor or a diode when no electric current is supplying to it are pure thermal noises that do not contain the so-called 1/f noise that is inversely proportional to the frequency f, and that the pure thermal noises represent a perfect random phenomenon. According to the invention, there is provided a random pulse generator that utilizes the above phenomenon and is adapted to amplify thermal noises by means of an amplifier to produce random analog pulse signals, transform the analog pulses into rectangular pulses and taking out the rectangular pulses for use. Thus, a random pulse generator according to the invention supplies random pulse signals that can be used for generating the natural random numbers.
In the second aspect of the invention, random pulses generated from a random pulse generator according to the invention are taken out as pulse signals and the time intervals between the random pulse signals and the succeeding pulse signals that are generated immediately after the respective first random pulse signals are measured and the measured values are supplied as the true physical random numbers. In case of time measurement with a n-bit counter, this invention use the measured value of the n bit number (n: integer, e.g., 8-bits: 0-255) as the true physical random numbers.
In the third aspect of the invention, the number of random pulses within a predetermined time period generated by a random pulse generator according to the invention are counted and one digit number or several-digits number of the counted relative frequency values are supplied as the true physical random numbers.
In the fourth aspect of the invention, random pulses generated by a random pulse generator according to the invention are taken out as pulse signals and the pulse frequencies within a predetermined time period or the time intervals between the random pulse signals and the succeeding pulse signals that are generated immediately after the respective first random pulse signals are measured so that the pulse peak value of one of the measured random pulse signals is selected as threshold value of a pulse peak discriminator in order to generate the true random numbers at a required random number generating speed
In the fifth aspect of the invention, a thermal noise generating element such as a resistor or a diode and other electronic circuits are contained integrally in an IC card or an IC chip provided with an information processing circuit and the information processing circuit are fed with physical random numbers for the purpose of personal identification, encoding and other purposes in computer telecommunications or mail-order business or for using it as a probability generator in a game machine.